Multiple Gestation & Twins — Placenta, Fetal Membranes & Twinning

Multiple Gestation & Twins MCQs: practice questions

Sample Multiple Gestation & Twins multiple-choice questions from Placenta, Fetal Membranes & Twinning.

1. How many zygotes form dizygotic twins?

   • A. Six
   • B. Two
   • C. Three
   • D. One
   • E. Four

2. What does '222' describe in twin placentation?

   • A. Two fetuses, two umbilical cords, two yolk sacs
   • B. Two placentas, two chorions, and two amniotic sacs
   • C. One placenta, two chorions, two amniotic sacs
   • D. Two placentas, one chorion, two amniotic sacs
   • E. Two chorions, one placenta, two amniotic sacs

3. What placental arrangement is most characteristic of monozygotic twins when separation occurs early?

   • A. Monochorionic monoamniotic
   • B. No chorion
   • C. Dichorionic diamniotic
   • D. Single amniotic sac with two chorions
   • E. Monochorionic diamniotic only

4. What placental arrangement is typical of dizygotic twins?

   • A. One placenta, one chorion, two amniotic sacs
   • B. One placenta, one chorion, one amniotic sac
   • C. Two placentas, two chorions, and two amniotic sacs
   • D. Two placentas, one chorion, one amniotic sac
   • E. One placenta, two chorions, one amniotic sac

5. Which twin type is necessarily monozygotic?

   • A. All dichorionic twins
   • B. Conjoined twins
   • C. All diamniotic twins
   • D. All twins with two placentas
   • E. All twins with two chorions

6. What is the key developmental event producing monozygotic twins?

7. Can monozygotic twins have different sexes?

8. How many zygotes form monozygotic twins?

9. What term describes twins with one chorion and two amniotic sacs?

10. Which twin type is produced by fertilization of two secondary oocytes?

11. What is the genetic relationship of monozygotic twins?

12. What twin arrangement is diamniotic monochorionic?

13. What is the relationship of conjoined twins to zygosity?

14. What is formed after fusion of the male and female pronuclei?

15. What is the main distinction between monoamniotic and diamniotic twins?

16. What is a conjoined twin?

17. What proportion of monozygotic twins have the same '222' arrangement in the developmental sequence?

18. What is the role of the centriole pair from the sperm in early monozygotic development?

19. What is the fundamental difference between monozygotic and dizygotic twins?

20. What term describes twins with two chorions and two amniotic sacs?

21. What is the developmental source of monozygotic twins?

22. What is the source of the second polar body in the zygote used in the monozygotic-twinning sequence?

23. What is the main placental distinction between monochorionic and dichorionic twins?

24. Which structure surrounds the morula during the early twinning sequence?

25. Can dizygotic twins have different sexes?

26. What twin arrangement is diamniotic dichorionic?

27. At what developmental stage is twin embryogenesis described as becoming active in the developmental figure?

28. What is a chimeric morula in the context of twinning?

29. What is the genetic relationship of dizygotic twins?

30. What structure splits during the classic monozygotic twinning process described in the developmental sequence?